This invention relates to a locking device for locking a cover of a device whose interior has to be kept blacked out, such as a film winder.
Most photographic devices for processing photosensitive material, such as a dark box for rewinding undeveloped film from one cartridge to another, are provided with a locking means for locking a cover plate of the device after the cover plate is closed on inner mechanism is activated to prevent an accident in which the cover plate opens unexpectedly so that the photographic film or paper inside is exposed to light.
A conventional such locking means is shown in FIG. 10. It comprises a locking lever 3 provided inside a case 2 having an openable cover plate 1, and a hook 1a fixed to the back of the cover plate 1. The locking lever 3 is pivotable about a hinge 5 and biased by a spring 4 coupled to a bracket 2.times. provided inside the case 2.
A solenoid 6 has a rod 6a coupled to the locking lever 3 to lock the cover plate 1. When the mechanism in the case 2 is activated, it produces a signal to energize the solenoid 6. When energized, the solenoid 6 moves the locking lever 3 from the position shown by chain line to the position shown by solid line, locking the cover plate 1. A reset push button 7 is provided for forcibly unlocking the cover plate 1 so that the cover plate can be opened to inspect the inside of the device even while the device is in operation.
With this conventional locking device, if the photographic device should malfunction or fail, it is possible to open the cover plate to inspect the inside of the device by pressing the reset button after confirming that the cover plate may be opened.
In the case of a locking device of the type in which a knob plate is provided on the cover plate so that the cover plate can be locked by closing it and moving the knob plate, and in which other parts of the photographic device can be operated by moving the knob plate, in order to unlock the cover plate and open it to inspect the inside of the photographic device while it is in operation, the other parts of the device linked to the knob plate will be influenced. This sometimes makes it impossible to unlock the cover plate.
It is therefore desirable that the locking device have an unlocking means which can unlock the cover plate without affecting any other parts of the photographic device.
An object of this invention is to provide a locking device for use in a photographic device provided with an openable light-shield cover adapted to be locked in position by moving a knob, the locking device being provided with an unlocking means capable of unlocking the cover without moving the knob even if the movement of the knob is operatively associated with the operation of other parts of the photographic device so that cover can be opened in an emergency by operating the unlocking means.